Hello I am new but hey. I have a 1960 Ford F-100 and the body is in decent shape. It looks like it has been painted before. I went and wet sanded to just clean it up and smooth it up and then I put some black rattle can primer on it to just make it one color for now. I know I have to take the primer off but I was wondering if I could just scuff it up and but that epoxy primer on top of the old paint. I will be grinding some areas down to bare metal and was wondering if I use that phosphoric acid to prevent rust or to make the epoxy primer to stick. When I put the acid on do I have to clean it off? I also wanted to just make the primer the color. Instead of shooting a shiny paint. Do I just color the epoxy spray it one sand it smooth and I am done or what? thanks for all the help.

You can coat epoxy or urethane primers over old paint. I personally would not, but you can. It won't craze the paint like spraying laquer on old enamel. But you would really be better off just sanding it down to the factory primer, at least. (especially since it's already had at least one re-paint.)

Acid etching is not necesary unless the metal has had a chance to surface rust enough to cause minor pitting. Without pitting, just knock off that minor surface rust with a D/A sander. With major pitting, acid will not do as well as blasting.

If you let the acid dry on the surface, it will leave a weird chalky surface on the metal. If you rinse it off (like the directions tell you) its going to flash rust again.

When I use it, I wipe it dry, then use a D/A to get the weird stuff off.

Making the primer the topcoat is a cool way to go, but you didn't mention the color.

If black is the way, I like using PPG's DP-90. It can be your bare metal primer, then just turn around and use it on top of your blocking primer. (use blocking primer too, like K-36, the DP wont cover filler very well) Just thin it down with warm temp reducer when using it as a topcoat so you can get a wet coat without tiger-striping.

If you want a color, you can tint K-36 with a topcoat color. But the best method is to use a two part base clear with no clear coat. Flat paint you will have.

Don't color sand your flat paint. Leave it as it comes out of the gun.

You can coat epoxy or urethane primers over old paint. I personally would not, but you can. It won't craze the paint like spraying laquer on old enamel. But you would really be better off just sanding it down to the factory primer, at least. (especially since it's already had at least one re-paint.)

Acid etching is not necesary unless the metal has had a chance to surface rust enough to cause minor pitting. Without pitting, just knock off that minor surface rust with a D/A sander. With major pitting, acid will not do as well as blasting.

If you let the acid dry on the surface, it will leave a weird chalky surface on the metal. If you rinse it off (like the directions tell you) its going to flash rust again.

When I use it, I wipe it dry, then use a D/A to get the weird stuff off.

Making the primer the topcoat is a cool way to go, but you didn't mention the color.

If black is the way, I like using PPG's DP-90. It can be your bare metal primer, then just turn around and use it on top of your blocking primer. (use blocking primer too, like K-36, the DP wont cover filler very well) Just thin it down with warm temp reducer when using it as a topcoat so you can get a wet coat without tiger-striping.

If you want a color, you can tint K-36 with a topcoat color. But the best method is to use a two part base clear with no clear coat. Flat paint you will have.

Don't color sand your flat paint. Leave it as it comes out of the gun.

Hey it is me again. Thanks for the reply. It sounds like I have to strip it down all the way but I don't know. I was thinking maybe I should paint it a shiny solid color. Like blue or white,something that looks good. Non metallic! About the primering with that ok here is the scenerio: scuff up the old paint to primer or almost primer. It has been repainted. Grind out the rust and stuff. feather the edges and bondo the dents. Ok now I have bear metal and bondo. Now what? The bondo absorbs moisture and the metal rust. Now what kind of primer do I use? ie: primer filler or the sealer like epoxy? I hope you guys understand what is going on. Then after that what do I use to show the lows and highs like black primer? Then after the wet sanding is all done throw the shiny new paint on? What color would look good with that year of truck do you guys think? Thanks and please keep on replying to the top thread too.

Sand your car with 400 grit sand paper, bondo spots can be done with 80 or 240 grit. Once you have done that and the bondo spots you are ready to primer. Your primer should be 4 parts reducer to 1 part primer with 1 part hardner, if I remember correctly. (depends on certain brands as well) You do not have to go black to see high and low spots. A yellow color primer can show them as well. Once primered and you have a nice even coat sand the paint job and feel with the palm of your hand for scratches, high and low parts, etc. Sand those down, if it needs more bondo work or parts that need to be taken down do it at this step. Once completed you are better off giving it another coat of primer. Once you are satisfied, blow the dust off of the car, fix the masking if it needs to be done, and you are then ready for base paint!! If you are painting your car in a garage or outside, I suggest you wipe down any surfaces for dust, and get the floor/ground wet. Good luck Try to post before and after pics once completed. Will be nice to see the finished car.

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